• Michal Schmidt's avatar
    rtnetlink: fix userspace API breakage for iproute2 < v3.9.0 · e5eca6d4
    Michal Schmidt authored
    When running RHEL6 userspace on a current upstream kernel, "ip link"
    fails to show VF information.
    
    The reason is a kernel<->userspace API change introduced by commit
    88c5b5ce ("rtnetlink: Call nlmsg_parse() with correct header length"),
    after which the kernel does not see iproute2's IFLA_EXT_MASK attribute
    in the netlink request.
    
    iproute2 adjusted for the API change in its commit 63338dca4513
    ("libnetlink: Use ifinfomsg instead of rtgenmsg in rtnl_wilddump_req_filter").
    
    The problem has been noticed before:
    http://marc.info/?l=linux-netdev&m=136692296022182&w=2
    (Subject: Re: getting VF link info seems to be broken in 3.9-rc8)
    
    We can do better than tell those with old userspace to upgrade. We can
    recognize the old iproute2 in the kernel by checking the netlink message
    length. Even when including the IFLA_EXT_MASK attribute, its netlink
    message is shorter than struct ifinfomsg.
    
    With this patch "ip link" shows VF information in both old and new
    iproute2 versions.
    Signed-off-by: default avatarMichal Schmidt <mschmidt@redhat.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    e5eca6d4
rtnetlink.c 72.3 KB